PDT was built only as a "PHP Development Tools framework". In the PHP world where there are hundreds of core extensions and dozens of frameworks it is impossible to support all of them.

But... a feature request is a feature request. And feature requests are meant to be resolved. Applying simple logic rules derives that - "PDT Gets Smarty".

His post both links to and gives an example of their integration. All it takes is downloading a single package and installing it into Eclipse. Check out the project's Googlecode page for more information.